Helleborus plant named ‘COSEH 4500’

Abstract

A new and distinct cultivar of Helleborus plant named ‘COSEH 4500’, characterized by its upright and mounding plant habit; uniform and freely flowering habit; dark green-colored leaves; freely and early flowering habit; single white-colored flowers; and good garden performance.

Claims

1. A new and distinct Helleborus plant named ‘COSEH 4500’ as illustrated and described.

Description

BRIEF DESCRIPTION OF THE PHOTOGRAPHS

(1) The accompanying colored photographs illustrate the overall appearance of the new Helleborus plant showing the colors as true as it is reasonably possible to obtain in colored reproductions of this type. Colors in the photographs may differ slightly from the color values cited in the detailed botanical description which accurately describe the colors of the new Helleborus plant.

(2) The photograph on the first sheet is a side perspective view of a typical flowering plant of ‘COSEH 4500’ grown in a container.

(3) The photograph on the second sheet is a close-up view of a typical flower of ‘COSEH 4500’.

DETAILED BOTANICAL DESCRIPTION

(4) The aforementioned photographs and following observations, measurements and values describe plants grown during the autumn and winter in 13-cm containers in a glass-covered greenhouse in Glandorf, Germany and under cultural practices typical of commercial Helleborus production. During the production of the plants, day temperatures ranged from 12° C. to 32° C. and night temperatures ranged from 3° C. to 18° C. Plants were 16 months old when the photographs and the description were taken. In the following description, color references are made to The Royal Horticultural Society Colour Chart, 2015 Edition, except where general terms of ordinary dictionary significance are used. Botanical classification: Helleborus×ericsmithii×Helleborus×hybridus ‘COSEH 4500’. Parentage: Female, or seed, parent.—Proprietary selection of Helleborus×ericsmithii identified as code number HE 10843, not patented. Male, or pollen, parent.—Unnamed seedling selection of Helleborus×hybridus, not patented. Propagation: Type.—By tissue culture. Time to initiate roots, winter.—About two months at temperatures about 12° C. Time to produce a rooted young plant, winter.—About six months at temperatures ranging from 4° C. to 15° C. Root description.—Thick to thin, fleshy; typically white to brown in color, actual color of the roots is dependent on substrate composition, water quality, fertilizer type and formulation, substrate temperature and physiological age of roots. Rooting habit.—Sparse. Plant description: Plant and growth habit.—Herbaceous perennial; upright and mounding plant habit with flowers held above and beyond the foliar plane; plant shape, roughly flattened globular; moderately vigorous growth habit; moderate growth rate. Plant height, soil level to top of foliar plane.—About 24 cm. Plant height, soil level to top of flowers.—About 33.6 cm. Plant diameter (area of spread).—About 50.5 cm. Leaf description: Arrangement.—Leaves arranged in a basal rosette; leaves palmately compound with typically five, or occasionally seven, leaflets per leaf. Leaf length.—About 24.9 cm. Leaf width.—About 24.9 cm. Leaflet length.—About 16.1 cm. Leaflet width.—About 7.4 cm. Leaf shape.—Palmate; reniform in outline. Leaflet shape.—Ovate, elliptic and obovate. Leaflet apex.—Apiculate. Leaflet base.—Attenuate. Leaflet margin.—Serrate; slightly undulate. Leaflet texture and luster, upper surface.—Smooth, glabrous; slightly rugose; leathery; glossy. Leaflet texture and luster, lower surface.—Smooth, glabrous; slightly rugose; leathery; moderately glossy. Leaflet venation pattern.—Pinnate. Leaflet color.—Developing leaflets, upper surface: Close to N137A. Developing leaflets, lower surface: Close to 147B. Fully developed leaflets, upper surface: Close to darker than between 147A and N189A; venation, close to 143A. Fully developed leaflets, lower surface: Close to 147B; venation, close to 200B to 200C. Petioles.—Length: About 18.1 cm. Diameter: About 7.5 mm. Strength: Strong. Texture and luster, upper and lower surfaces: Smooth, glabrous; glossy. Color, upper and lower surfaces: Close to 146A to 146B, heavily speckled and tinged with close to 200B to 200C. Flower description: Flower shape and habit.—Single rotate flowers arranged solitary or in panicles; freely and uniform flowering habit with about ten flowers per inflorescence and about 70 flowers developing per plant; flowers facing outwardly to slightly nodding. Fragrance.—None detected. Natural flowering season.—Plants begin flowering about ten months after planting; plants flower during the winter in Germany. Flower longevity on the plant.—About ten days; flowers not persi stent. Flower buds.—Length: About 2.3 cm. Diameter: About 1.4 cm. Shape: Elliptic. Texture and luster: Glabrous; matte. Color: Close to 145D. Inflorescence height.—About 29.9 cm. Inflorescence diameter.—About 18.9 cm. Flower diameter.—About 8.6 cm. Flower depth (height).—About 2.6 cm. Petals.—Transformed into nectaries. Sepals.—Quantity and arrangement: About five, arranged in a single whorl. Length: About 4.3 cm. Width: About 3.5 cm. Shape: Broadly ovate. Apex: Obtuse. Base: Cuneate. Margin: Entire. Texture and luster, upper and lower surfaces: Glabrous; matte. Color: When opening, upper and lower surfaces: Close to 155C. Fully opened, upper surface: Close to 157B to 157C. When opening, lower surface: Close to 157C to 157D. Flower bracts.—Quantity per flower: Typically one. Length: About 4.5 cm. Width: About 2.6 cm. Shape: Ovate. Apex: Acute. Base: Broadly cuneate. Margin: Entire; distally, occasionally serrated; slightly undulate. Color, upper surface: Close to NN137A. Color, lower surface: Close to 147B; venation, close to N186C. Peduncles.—Length: About 28.7 cm. Diameter: About 1.1 cm. Aspect: About 12.5° from vertical. Strength: Strong. Texture and luster: Glabrous; moderately glossy. Color: Close to 146C to 146D, densely speckled and flushed with close to 178A. Pedicels.—Length: About 2.6 cm. Diameter: About 2.5 mm. Aspect: About 25° from peduncle axis. Strength: Moderately strong. Texture and luster: Glabrous; glossy. Color: Close to 145A to 145B; proximally, finely speckled and tinged with close to 177B to 177C. Reproductive organs.—Stamens: Quantity per flower: About 70. Filament length: About 1.8 cm. Filament color: Close to NN155D. Anther shape: Reniform; basifixed. Anther size: About 1.75 mm by 2 mm. Anther color: Close to 150C. Pollen amount: Scarce. Pollen color: Close to 4D. Pistils: Quantity per flower: About five. Pistil length: About 1.4 cm. Stigma diameter: About 0.3 mm. Stigma shape: Club-shaped. Stigma color: Close to 155A. Style length: About 1.375 cm. Style color: Close to 184C to 184D. Ovary color: Close to 145A to 145B. Nectaries (transformed petals): Quantity per flower: About 14. Length: About 1.2 cm. Diameter: About 3.5 mm. Shape: Tubular, flattened. Texture and luster, inner surface: Smooth, glabrous; matte. Texture and luster, outer surface: Smooth, glabrous; glossy. Color, immature, inner and outer surfaces: Close to 144B; towards the apex, close to 151C to 151D. Color, mature, inner and outer surfaces: Close to 144A; towards the apex, close to 151A to 151B; venation, close to 146D, distally, close to 12A; with development, color towards the apex becoming closer to 153C to 153D. Seeds and fruits.—Seed and fruit development have not been observed on plants of the new Helleborus. Garden performance: Plants of the new Helleborus have been observed to have good garden performance and to tolerate rain, wind and to be suitable for USDA Hardiness Zones 5 through 9. Pathogen & pest resistance: Plants of the new Helleborus have not been observed to be resistant to pathogens and pests common to Helleborus plants.